Conventionally, an electric power steering device is known for using a drive unit in which a motor and its control unit are disposed in one body. The drive unit of the electric power steering device disclosed in Japanese Patent Laid-Open No. 2003-204654 ('654), has a terminal on the control unit side that is affixed to a heat sink by a resin mold, and affixed to a terminal on the motor side by way a screw in a screw-fitted manner. In such connection structure of the terminals, it is necessary to remove the screws one by one when the motor and the control unit are separated. Therefore, when the control unit is broken and the control unit has to be removed from the motor for replacement, for example, all the screws have to be unscrewed and removed, thereby making such replacement procedure very time-consuming. In addition, a replaced control unit has to be attached to the motor by screwing all those screws again, which is also very time-consuming.
Therefore, for example, by shaping one of the motor side terminal and the control unit side terminal in a “male” shape and the other terminal in a “female” shape, the terminals of the motor and the control unit may attach and detach without the use of screws. However, in such insert-fit structure for connecting terminals, an appropriate force for inserting/pulling out the terminal needs to be applied when the terminals on the control unit side are inserted into or pulled out from the terminals on the motor side. Further, in a course of manually applying such “insert-pullout” force in the insert-fit structure, the control unit may be tilted thereby inadvertently generating an un-desired force on the terminals in an un-expected direction other than an insertion/pullout direction of those terminals (i.e., an insertion/pullout direction is simplified as an “insertion direction” hereinafter). Application of such un-desired force in the un-expected direction may, therefore, lead to a situation in which smooth insertion and/or pull-out of those terminals is disabled, or, in other words, those terminals may be broken by such force.
Further, when the drive unit has a high output motor by receiving a large electric current, the terminal on the control unit side may be desirably connected to the terminal on the motor side very tightly. Such a tight connection between the control unit and the motor may make it more difficult to manually connect and/or remove the control unit to/from the motor, because the above-mentioned insert-pullout force may be increased when the connection is tight.